Experts discuss design, evolution of the Xience and Promus stents

SAN FRANCISCO — Technological advances and design evolutions have enhanced drug-eluting stent development in recent years. Modifications in stent design and delivery of the everolimus-eluting stent (Xience, Abbott Vascular) and Promus Element (Boston Scientific) platforms were the focus of discussions by James B. Hermiller, MD, and Hyo-Soo Kim, MD, PhD, at TCT 2013, with particular emphasis on safety data established in recent clinical trials.

Changes implemented since the original Xience V cobalt-chromium EES platform include taller nonlinear links and longer rings to enhance flexibility of the Xience Prime stent and an integrated tip and less-compliant balloon to improve delivery of the Xience Xpedition stent, said Hermiller, of St. Vincent Heart Center, Indianapolis, IN.

Design improvements of the Promus Element EES stent include superior flexibility and conformability, a thin strut and a platinum-chromium alloy for enhanced visibility, according to Kim, of Seoul National University Hospital, Korea.

Emerging data for Xience

Thirty-three randomized trials comprising more than 43,000 patients have been conducted on the Xience stents.

Hermiller referenced a recent meta-analysis published in JACC Cardiovascular Interventions of EES vs. paclitaxel-eluting stents (Taxus, Boston Scientific) in CAD using 3-year results from the SPIRIT Clinical Trials Program. At 3 years, EES was superior to PES for target lesion failure (8.9% vs. 12.5%; HR 0.71; 95% CI 0.59-0.85), all-cause mortality (3.2% vs. 5.1%; HR 0.65; 95% CI 0.49-0.86), MI (3.2% vs. 5.1%; HR 0.64; 95% CI 0.48-0.85), cardiac death/MI (4.4% vs. 6.3%; HR 0.70; 95% CI 0.54-0.90), ischemia-driven target vessel revascularization (6% vs. 8.2%; HR 0.72; 95% CI, 0.58-0.90), stent thrombosis (0.7% vs. 1.7%; HR 0.45; 95% CI 0.26-0.78) and MACE (9.4% vs. 13%; HR 0.71; 95% CI, 0.60-0.85). A pooled database analysis of the SPIRIT II, III, IV and COMPARE trials yielded similar results at 2 years for ischemic TLR (4.1% vs. 6.6%; HR 0.60; 95% CI 0.48-0.75) and definite/probable stent thrombosis (0.7% vs. 2.3%; HR 0.30; 95% CI, 0.19-0.47).

Moreover, “five network meta-analyses and EXAMINATION [trial data] suggest lower stent thrombosis rates, even in patients with STEMI,” Hermiller said at the presentation.

Addition data on dual antiplatelet therapy interruption suggest there is a low rate of stent thrombosis with the Xience platform, even after 1 month of interruption, he said.

Emerging data for Promus

Improvements to the Promus Element stent have “resulted in promising results, at least comparable to Xience V and Resolute,” Kim said while discussing findings from the PLATINUM and HOST-ASSURE randomized trials.

In PLATINUM, Promus Element was noninferior to Xience for the primary endpoint of TLF at 1 year (3.3% vs. 3%; HR 1.12; 95% CI 0.63-1.98), but diverged at 3 years (2.9% vs. 4.3%; HR 0.68; 95% CI 0.39-1.18). Through 3-year follow-up, event rates were low in the studied patient population in both arms. There were no significant differences between groups in rates of all-cause death or MI (6% vs. 6.3%; HR 0.95; 95% CI 0.63-1.45), stent thrombosis (0.7% vs. 0.5%; HR 1.23; 95% CI 0.33-4.57) or ischemia-driven repeat revascularization (1.9% vs. 3.2%; HR 0.61; 95% CI, 0.31-1.20). Three-year results confirm the excellent safety and efficacy profile of the Promus Element EES, Kim said.

HOST-ASSURE compared the Promus Element and Endeavor Resolute (Medtronic) stents. Target lesion failure at 1 year was approximately 2.9% in both groups (HR 1.00; 95% CI 0.67-1.50). Clinical events at 1 year months were the same. Definite/probable stent thrombosis at 1 year was about 0.36% with Promus and 0.67% with the other (P=.229).

“Longitudinal stent deformation is a potential concern for thin-strut stents. But it occurs in a very low rate and has little impact on clinical outcomes. It will be solved by the new design of the Promus Premier stent,” he said.

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For more information:

Hermiller JB. From Xience V to Prime to Xpedition: Stent design evolution and clinical trial results (SPIRIT and others).

Kim HS. The Promus Element everolimus-eluting stent: Design considerations and clinical trial results (from PLATINUM to HOST-ASSURE). Both presented at: TCT 2013; Oct. 27-Nov. 1, 2013; San Francisco.

Disclosure: Hermiller reports receiving consulting fees/honoraria from Abbott, Boston Scientific, Edwards Lifesciences, Medtronic CardioVascular and St. Jude Medical, and served on the speaker’s bureau for The Medicines Company. Kim reports receiving grant/research support from Boston Scientific Korea and Medtronic CardioVascular Korea.